(unreadchar): For unreading an ASCII char

thru a buffer or marker, really decrement point or the marker position.

1 files changed, 34 insertions, 2 deletions

diff --git a/src/lread.c b/src/lread.c
index e69e3f86943..144f991223f 100644
--- a/src/lread.c
+++ b/src/lread.c
@@ -268,9 +268,41 @@ unreadchar (readcharfun, c)
        since readchar didn't advance it when we read it.  */
     ;
   else if (BUFFERP (readcharfun))
-    readchar_backlog++;
+    {
+      if (!SINGLE_BYTE_CHAR_P (c))
+        readchar_backlog++;
+      else
+        {
+          struct buffer *b = XBUFFER (readcharfun);
+          int bytepos = BUF_PT_BYTE (b);
+
+          BUF_PT (b)--;
+          if (! NILP (b->enable_multibyte_characters))
+            BUF_DEC_POS (b, bytepos);
+          else
+            bytepos--;
+
+          BUF_PT_BYTE (b) = bytepos;
+        }
+    }
   else if (MARKERP (readcharfun))
-    readchar_backlog++;
+    {
+      if (!SINGLE_BYTE_CHAR_P (c))
+        readchar_backlog++;
+      else
+        {
+          struct buffer *b = XMARKER (readcharfun)->buffer;
+          int bytepos = XMARKER (readcharfun)->bytepos;
+
+          XMARKER (readcharfun)->charpos--;
+          if (! NILP (b->enable_multibyte_characters))
+            BUF_DEC_POS (b, bytepos);
+          else
+            bytepos--;
+
+          XMARKER (readcharfun)->bytepos = bytepos;
+        }
+    }
   else if (STRINGP (readcharfun))
     read_from_string_index--;
   else if (EQ (readcharfun, Qget_file_char))